Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
import sys
sys.setrecursionlimit(3000)
import queue
h,w=map(int,input().split())
s=['#'*(w+2)]+['#'+input()+'#' for _ in [0]*h]+['#'*(w+2)]
l=[[0]*(w+2) for _ in [0]*(h+2)]
for i in range(h+2):
    for j in range(w+2):
        if s[i][j]=='#':
            l[i][j]=-1
L=queue.Queue()
L.put([1,1])
while not L.empty():
    n=L.get()
    for dx,dy in [(1,0),(-1,0),(0,1),(0,-1)]:
        if l[n[0]+dx][n[1]+dy]==0 and [n[0]+dx,n[1]+dy]!=[1,1]:
            l[n[0]+dx][n[1]+dy]=l[n[0]][n[1]]+1
            L.put([n[0]+dx,n[1]+dy])

if l[h][w]==0:print(-1)
else:print(h*w-l[h][w]-(sum(x.count('#') for x in s)-2*h-2*w-4)-1)